Compression coding means a series of signal processing techniques for transmitting digitalized information via a communication circuit or storing the digitalized information in a form suitable for a storage medium. As targets of compression coding, there are audio, video, characters, etc. In particular, a technique for performing compression coding on video is called video sequence compression. A video sequence is generally characterized in having spatial redundancy or temporal redundancy.
A scalable video coded bit stream can be selectively decoded in part only. For instance, a decoder having low complexity is capable of decoding a basic layer and a bit stream at a low data rate can be extracted for transmission via a network having a limited capacity. In order to generate images of high resolution more gradually, an image quality of a sequence needs to be raised step by step.